Summary/Abstract: Research Project (B) According to the Centers for Disease Control and Prevention, about 1 in 400 children are born with some degree of hearing loss. It is well-established that children with even modest degrees of hearing loss (CHL) suffer from a breadth of language and communication delays throughout development compared to matched children with normal hearing (CNH). These deficits generally correlate with hearing aid (HA) audibility and usage measures, which is especially pertinent as there is significant variability in HA usage and fit within the CHL population. Further, children with severe-to-profound hearing loss also exhibit impairments in other cognitive domains such as working memory, attention, and executive function, and these deficits reliably correlate with measures of language function in these children. Nonetheless, the degree to which these impairments in other cognitive domains are also present in the less severe CHL population is unknown. More broadly, it is unclear whether cognitive deficits exist above and beyond the impact of language in those with milder hearing loss, and it is very difficult to dissociate the contributions of language to other cognitive functions (e.g., attention) using behavioral tests alone. This proposal seeks to fill these knowledge gaps, and provide pivotal new data clarifying the impact of hearing loss on cognitive function, development, and brain activity in children. Our groundbreaking preliminary work is the first to show that CHL exhibit altered neuronal dynamics during high-order verbal and nonverbal cognitive processing compared to CNH, and suggests that neuroimaging is a powerful avenue by which to differentiate the impact of hearing loss on language function versus other cognitive domains. In the proposed study, we will further identify the effects of hearing loss on verbal and nonverbal higher-order cognition. We will enroll a large developmental cohort of CHL and demographically-matched CNH to undergo multimodal imaging with magnetoencephalography (MEG) during a battery of cognitive tests, as well as structural MRI. In Aim 1, we will probe the behavioral and neural markers of verbal cognitive function and development in CHL and CNH. In Aim 2, we will quantify behavior and neurophysiology during performance of nonverbal cognitive tasks in the same groups. In Aim 3, we will clarify the impact of age at intervention, HA fit (e.g., aided audibility), and HA use on these parameters in CHL. We hypothesize that CHL will exhibit altered behavioral performance and dynamic neural patterns during these tasks. Specifically, we postulate that neural aberrations will be found in frontal and parietal language regions during verbal cognitive tasks, but that dorsal attention and frontal executive function will also be aberrant during nonverbal cognitive tasks, indicative of a general cognitive deficit over-and-above language function. Finally, we posit that quality of HA fit, amount of HA use, and age at intervention will partially mediate the relationship between performance and neural dynamics in CHL. The results of this study have the potential to dramatically improve our understanding of behavioral outcomes in this population, and also to shape our knowledge of the impact of sensory experience on the neural dynamics serving higher-order cognition.